Knitting machine with means to heat yarn en route to the needles



KNITTING MACHINE WITH MEANS TO HEAT YARN ENROUTE TO THE NEEDLES OriginalFiled July 31, 1957 BURLESON Sept. 25, 1962 2 SheetsSheet 1 2 Jim 55.9:

R m V m AARON BURLES ATTORNEYS Sept. 25, 1962 A. BURLESON 3,055,198

KNITTING MACHINE WITH MEANS TO HEAT YARN ENROUTE TO THE NEEDLES OriginalFiled July 51, 1957 2 Sheets-Sheet 2 no.3. F104.

-INV-ENTOR AARON BURLE SON ATTORNEYS Uite 3,055,198 KNITTING MACHINEWITH MEANS T l-EA'I YARN EN ROUTE TO THE NEEDLES Aaron Burleson,Burlington, N.C., assignor to Burlington Industries, Inc, Greensboro,N.C., a corporation of Delaware Original application July 31, 1957, Ser.No. 675,472. Di-

vided and this application Mar. 9, 1960, Ser. No. 13,746 4 Claims. (Cl.66125) This invention relates to knitting, and in particular to animproved method of knitting with thermoplastic yarns, such as nylon. Theinvention relates also to improvements in circular knitting machines,and to novel knitted fabrics manufactured thereby. This application is adivision of my co-pending application Serial No. 675,472, filed July 31,1957.

In the circular knitting of seamless hosiery, a constant number ofneedles is utilized throughout the welt, leg and foot. In order to shapethe stockings to the contours of the leg, the stitch length is varied asthe knitting proceeds. At the top of the stocking, as will be evident,the stitch is larger than in the ankle and foot areas. There are,however, limitations to the shaping of stockings by means of stitchlength variation. If the cylinder of the knitting machine is adequate indiameter to make a welt of generous size, the ankle and foot areas ofthe stocking are prone to be too large, tightening of the stitch inthese areas being insufficient to narrow them down to desired relativesize. If a knitting machine of smaller cylinder diameter is utilized, toproduce a stocking of acceptable fit in the angle and foot, the welt andknee areas of the stocking tend to be tight fitting. A compromise isusually effected, wherein the welt and knee areas are tighter than mightbe desired, and the ankle and foot areas looser. After knitting,seamless hosiery made of thermoplastic yarn can be further shaped byboarding, but the knee and welt areas still present a problem in thatthey have a tendency to be too tight.

One procedure hitherto utilized in overcoming this problem is topreshrink or preset the welt yarn before knitting, so that there can bebut little or no welt shrinkage after the hose have been knit. Asreceived from the manufacturer, nylon yarn usually has about or 12%residual shrinkage, and the welt yarn may be relaxed or shrunk to thisdegree by special treatment prior to knitting. In further processing ofthe hose so knit, the leg and foot are shrunk but the welt is not,whereby a welt of greater relative size is achieved. Preshrinkin-g ofthe welt yarn, however, increases its stiffness, and introduces otherdifiiculties. It is difiicult, for example, to knit preshrunk yarn so asto form loops properly inthe knitting machine, the yarn tending to betoo stifi and to not hold its shape as drawn by the needles and formedby the sinkers. In subsequent operations, stitches or loops that distortremain in this condition, causing distortion and crows fee or trackingin the finished fabric. The use of preshrunk welt yarn also introducesthe problems of uneven dyeing, non-uniformity of stretch between weltsand stitch breakdown, all of which lower the quality of the stockings.While improved fit may be achieved in this manner, then, othermanufacturing difficulties are introduced, and the quality of the goodsis lowered.

It is a principal object of the present invention to provide an improvedmethod of knitting with thermoplastic yarn, whereby uniform stitchformation is effected, and

the knitting operation is facilitated. A particular object' is theprovision of a method of knitting seamless hosiery having improved shapeand fit, and fabric clarity, particularly in the welts thereof. Arelated object is the provision of a method of knitting seamless hosieryutilizing 3,55,193 Patented Sept. 25, 1962 welt yarn directly from thepirn, without intermediate processing.

Another object of the invention is the provision of novel circularknitting machine structure, including yarn heating means in closeproximity to the cylinder thereof.

Yet another object of the invention is the provision of knitted fabriccomprising thermoplastic yarn relaxed and set in knitted shape duringthe knitting operation. A related object is the provision of a seamlessstocking of improved shape and fit, and outstanding quality. Furtherobjects will be in part evident, and in part pointed out hereinafter.

The invention and the novel features thereof may best be made clear fromthe following description and the accompanying drawing in which:

FIGURE 1 is a perspective view of the latch ring and knitting stationelements of a conventional seamless hosiery circular knitting machine,

FIGURE 2 is a side elevational view of the mechanism of FIGURE 1,partially broken away for the sake of clarity,

FIGURE 3 is a side elevational view of a seamless stocking knit inaccordance with the present invention, and

FIGURE 4 is an enlarged fragment of a representative portion of the bodyfabric of the stocking of FIGURE 3.

Referring to the drawings, FIGURE 1 illustrates a portion of aconventional seamless hosiery machine, which may be for example a400-needle Model KN Scott & Williams machine. As shown, the latch ring10 is pivotally mounted by means of pivot 12 between brackets 14extending upwardly from the bed plate (not shown) of the machine, andencloses the knitting station indicated generally as 16. At the knittingstation, a plurality of yarn fingers 18 are provided, the yarn fingersbeing individually retractable, and functioning as interchangeable yarnfeeds. The yarn fingers are pivotally mounted at 20 in the latch ringlug 22. A bracket 24 extends upwardly from latch ring lug 22, and fromthe outwardly turned bracket end 26 a tension spring 28 extends to theouter end of each yarn finger. On the opposite side of pivot 20, eachyarn finger is engaged from below by a thrust bar 30, operative inconventional manner from the main drum of the machine.

The yarn fingers are normally maintained in up or inoperative positionby their associated thrust bars, the springs 28 being thereby extended.Downward movement of any thrust bar, for example to the position 30',permits the engaged spring 28 to displace the associated feed finger 18to active position, as shown at 18 in FIG- URE 2, whereby the feedfinger is disposed in close proximity to the path of the knittingneedles 32. In FIGURE 2 is also illustrated the dial drive pinion 34,adapted to drive the dial 36 and its transfer jacks 38 in synchronismwith the rotary cylinder 39 of the machine, and the independent needles32 carried thereby. The dial is surmounted by the usual dial cap 40.

The customary yarn guide plate 42 is mounted on the latch ring lug 22,and extends over the yarn fingers 18. The yarn guide plate 42 isprovided with a plurality of eyelets 44, and yarns 46 extend througheyelets 44 and the drilled inner ends of the yarn fingers 18. As shownin the drawing, yarns 46 extend to the inactive yarn fingers 18, and theyarn 46 extends to the finger 18' in operative or knitting position. Allmachine elements described to this point are conventional.

In accordance with the present invention, a heating element 50 isdisposed between the yarn guide plate 42 and the yarn fingers 18, as bybracket 52 extending from the latch ring lug, and extends generallytransversely of the yarn finger group. The heating element may be of anyconventional type, but preferably is an electrical heating element,supplied with current by the conductor 54. The heating element isdesirably constructed of metal and smooth surfaced, preferably beingchrome plated.

Function and operation of the apparatus illustrated in the drawing willnow be described, this illustrating also the method of the invention. Atthe beginning of the knitting operation, all yarns are inactive, andextend through their respective eyelets 44 and feed fingers 18 to thedial cap 40, where they are clamped by the usual means, not shown. Uponthe initiation of welt knitting the thrust rod 30 is lowered by movementof the main drum of the machine, and the engaged yarn finger 18' isthereby permitted to drop to active or operative position, asillustrated in the drawing, under the impetus of its spring 28. Thenylon welt yarn 46" is thereby drawn between the hooks of the knittingneedles 32 and taken in the hooks of the succeeding needles, and weltknitting proceeds.

In accordance with the present invention, the welt yarn 46' in beingmoved from the inactive dotted line position shown in FIGURE 2, to theactive position shown in solid lines therein, is brought into wipingcontact with the heating element 50. The heating element is maintainedat a temperature of about 450 F., and is preferably thermostaticallycontrolled. The heating element 50 may be of such size and shape thatfrom threefourths to one inch of the welt yarn in active position is incontact therewith. The traveling welt yarn is thereby heated to atemperature above about 220 F., to a temperature in the range of fromabout 22.0 to about 400 F.

The welt yarn may be nylon yarn as received from the manufacturer,having usually or 12% residual shrinkage. The yarn in passing theheating element 50 and being heated to the temperature specified issoftened and relaxed, and about one half the residual shrinkage is takenout in passage from the yarn guide plate 42 to the needles of themachine.

The softened and pliable yarn remains at elevated temperature whilepassing through the yarn finger 18 and while engaged by the hooks of theneedles 32, and through the stitch formation. That is the yarn remainshot while stitches are formed therein by the needle hooks and sinkers,and then cools and sets in knitted shape. Cooling and setting of theyarn takes place, usually, after about one half revolution of thecylinder. The softened yarn facilitates uniform stitch formation, andthe stitches so formed maintain their shape in further processing of thestocking, and resist distortion.

At the end of the welt, the thrust rod 30 and the yarn finger 18' areelevated into inoperative position, whereby the welt yarn 46' isdisplaced to the dotted line position indicated in FIGURE 2, out ofcontact with the heating element. Substantially simultaneously, a bodyyarn 46 is dropped into the knitting, and knitting of the leg proceeds.As shown, the yarns 46, which may be for example a body yarn used in theleg and foot of the stocking and a heel and toe yarn, may be threadedthrough eyelets 44 displaced outwardly from the heating element 50, sothat these yarns are not heated when active. In this manner, the methodof invention may be confined to the welt of the stocking, with theattendant advantages of improved fit and high quality. As will be understood, the method of the invention may be utilized in other portions ofthe stockings as well, or in the entire stocking. As will be evidentfrom the drawing, all yarns threaded through the row of eyeletsimmediately above the heating element will contact the heating elementwhen active, and all yarns threaded through the row of eyelets disposedoutwardly of the heating element will be unaffected thereby when active.

FIGURE 3 illustrates a conventional stocking indicated generally as 52,including the usual welt 54, leg 56, foot 58, heel 60 and toe 62. FIGURE4 represents the appearance of a body yarn 64 knit in accordance withthe present invention, the loops thereof being characterized byuniformly excellent shape, whereby the fabric exhibits excellent clarityand general appearance, and freedom from distortion and tracking.

In accordance with the procedure described, the heating element mayremain at operative temperature at all times. In special circumstances,the heating element may be permitted to cool during portions of theknitting cycle, and may be heated during other portions only, somepreliminary heat-up time being provided before yarn heating commences.Control of the heating element in this manner may be effected by asimple switch actuated by the main drum of the machine. It may bedesirable, in some cases, to provide means for raising the active yarnoff the heating element, in the event the machine stops for any reason.Such mechanism may be actuated, for example, by an inertia switch.

While heating of the yarn may be accomplished in simple fashion by theheating element described and illustrated, it will be evident that otherheating devices may be employed as well. For example, the yarn may beheated by passage through a tube, or by radiant or induction heating. Itis necessary only that the yarn be heated to proper temperature in closeproximity to the yarn feed, or to the needles, so that it remains insoftened condition while stitches are formed therein.

While the invention has been illustrated in connection with a circularhosiery knitting machine, it will be evident that it may be utilized inconnection with other types of knitting machines. Similary, theinvention may be utilized with thermoplastic yarns other than nylon.

It will thus be seen that there has been provided by this invention amachine in which the various objects herein-before set forth, togetherwith many practical advantages are successfully achieved. As variouspossible embodiments may be made of the several features of the aboveinvention, all without departing from the scope thereof, it is to beunderstood that all matter hereinbefore set forth or shown in theaccompanying drawing is to be interpreted as illustrative, and not in alimiting sense.

I claim:

1. In a circular knitting machine, a rotary cylinder with independentneedles, a yarn feed operative adjacent the path of said needles, andmeans for heating the yarn sufiiciently to soften it, said yarn heatingmeans being mounted adjacent the yarn path to said feed and in closeproximity along said path to said yarn feed, whereby said yarn remainsin softened condition during stitch formation.

2. In a circular knitting machine, a rotary cylinder with independentneedles, a group of individually retractable interchangeable yarn feedsoperative adjacent the path of said needles, and means for heating theyarn sufficiently to soften it, said yam heating means being mountedadjacent the yarn path to said group and in close proximity along saidpath to said yarn feed group, whereby said yarn remains in softenedcondition during stitch formation.

3. In a circular knitting machine, a rotary cylinder with independentneedles, 2. yarn feed finger retractable from operative positionadjacent the path of said needles to inoperative position spacedtherefrom, and a heating element for heating the yarn sufficiently tosoften it, said heating element being mounted in close proximity to saidfeed finger, said heating element being disposed adjacent the yarn pathto said feed finger when the latter is in operative position and inclose proximity to said finger along said path, whereby said yarnremains in softened condition during stitch formation.

4. In a circular knitting machine a rotary cylinder with independentneedles, a group of interchangeable yarn feed fingers individuallyretractable from operative position adjacent the path of said needles toinoperative position spaced therefrom, a yarn guide plate overlying saidfeed fingers, and a heating element mounted between said guide plate andsaid feed fingers, said heating element being disposed adjacent the yarnpath from said guide plate to at least one of said feed fingers inoperative position.

References Cited in the file of this patent UNITED STATES PATENTSG-reenwald Dec. 22, 1931 Schellenberg et a1. July 1, 1941 Alexander eta1. Oct. 18, 1949 Reading July 8, 1952

